1. Field of the Invention
The present invention relates to a disk type valve for use in valve means, for example, a water valve, a mixing valve, a flow path switching valve of an anus washer provided in a toilet, etc. More particularly, the present invention pertains to a disk type valve having disk-shaped valve bodies (disks) made of a ceramic material.
2. Description of the Related Art
Valve means (e.g., water valves, mixing valves, etc.) which have disk type valves serving as flow control valves have heretofore been widely employed. The disk type valve is generally arranged such that a pair of fixed and movable disks which is superposed one upon the other is disposed in a cylindrical valve casing in such a manner that the planes of the disks are perpendicular to the axis of the valve casing, these disks being provided with notches or openings for passing water.
The conventional disk type valve will be explained below with reference to FIGS. 2 to 5.
The reference numeral 12 denotes a cylindrical valve casing of a disk type valve 10. The central portion of the valve casing 12 is provided with a slit-shaped opening (hereinafter referred to as "slit") 14 from which a fluid, for example, water, hot water, mixed water, etc. (hereinafter referred to as "water") flows out as shown by the arrow. The valve casing 12 is installed in such a manner that one axial end portion A thereof projects outside from the body of the valve device (not shown). A movable disk (disk-shaped valve body) 16, shown in FIGS. 3 to 5, which is made of a ceramic material, for example, alumina (aluminium oxide), is fitted in the other axial end portion B of the valve casing 12 in such a manner that the disk 16 is movable within the plane thereof.
The movable disk 16 is provided with two substantially sectorial openings 18 for passing water. In addition, an elongate groove 24 through which a spindle 22 is connected to the movable disk 16 is formed in the reverse surface of the disk 16 with respect to the surface thereof which is in sliding contact with a fixed disk 30 (described later). The movable disk 16 is retained by means of an inward flange (retaining portion) 26 which is formed inside the valve casing 12, as shown in FIG. 2. It should be noted that the reference numeral 28 denotes a slipwasher which is interposed between the inward flange 26 and the movable disk 16 to enable the disk 16 to rotate smoothly.
A fixed disk 30 is installed inside the end portion B of the valve casing 12 in such a manner that the movable and fixed disks 16 and 30 are superposed one upon the other and the former is slidable on the latter, the fixed disk 30 being made of the same ceramic material as that used to form the movable disk 16 and having the same configuration as that of the disk 16. The reference numeral 32 denotes an elongate groove formed in the fixed disk 30. It should be noted that, although in the prior art shown in FIGS. 2 to 5 the disks 16 and 30 are provided with sectorial openings, there are cases where sectorial notches are provided therein.
An elongate leaf spring 34 is fitted in the elongate groove 32 provided in the fixed disk 30 in such a state that the central portion of the leaf spring 34 is arcuated. Two end portions of the leaf spring 34 are fitted into respective small holes 36 which are provided in the inner peripheral surface of the end portion B of the valve casing 12, thereby retaining the leaf spring 34. Accordingly, the fixed disk 30 is pressed against the movable disk 16 with an appropriate pressure applied by the biasing force from the leaf spring 34. It should be noted that the fixed disk 30 is prevented from rotating by the leaf spring 34.
The distal end portion (in the shape of a flat plate) of a spindle 22 is fitted in the elongate groove 24 provided in the movable disk 16. The central portion of the spindle 22 is rotatably supported by a holder portion 12a formed at the end A of the valve casing 12. Serrations are provided in the outer end portion of the spindle 22 so that a handle is engageable with the spindle 22 through the serrations.
It should be noted that the spindle 22 has a stop pin 38 radially projecting therefrom. The stop pin 38 is received in a slit 40 provided in the valve casing 12. The slit 40 is provided so as to extend through about 90.degree. with respect to the axis of the valve casing 12. Thus, the spindle 22 is rotatable about it own axis within the range of about 90.degree..
In addition, a collar 22T is provided on the spindle 22, the collar 22T being in sliding contact with the holder portion 12a.
In the disk type valve 10 arranged as stated above, as the spindle 22 is turned, the movable disk 16 rotates, causing a change in the degree at which the openings 18 in the movable disk 16 overlap those in the fixed disk 30, and thus enabling switching of the valve device between the open position and the closed postion and also permitting control of the flow rate. In this case, water flows into the disk type valve 10 from the end B of the valve casing 12, passes through the fixed and movable disks 30 and 16 in the mentioned order and flows out from the slit 14.
In the above-described conventional disk type valve 10, the fixed disk 30 is pressed against the movable disk 16 by means of the leaf spring 34, and pressure of the water flowing into the disk type valve 10 also acts in a direction to which the fixed disk 30 is pressed against the movable disk 16. Therefore, the movable disk 16 is slid in a state wherein it is pressed against the fixed disk 30 and the slip washer 28 with a pressure which is the sum of the biasing force from the leaf spring 34 and the water pressure, thus causing considerably high sliding resistance. The collar 22T of the spindle 22 may also be pressed against the holder portion 12a by the combination of the water pressure and the leaf spring pressure, which also causes high sliding resistance.
Under these circumstances, there has heretofore been a fear that the spindle 22 cannot be rotated, that is, the handle cannot be turned, unless strong torque is applied thereto, particularly when the water pressure is high or when the movable disk 16 cannot slide smoothly because the slip washer 28 has deteriorated.